The present invention relates generally to shielded connectors, and more particularly to small-sized connectors having improved opposing connector retention characteristics.
It is known that metal shields may be disposed on the exterior circumferential surface of box-shaped insulative housings of connectors for the purposes of preventing interference, such as electrical noise. One example of such a connector is disclosed in Japanese Utility Model Application Laid-Open No. Hei 5-34679, Japanese Patent Application Laid-Open No. Hei 10-83866, and others. The connector disclosed in these publications is one that is mounted to a substrate such as a printed circuit board and is formed so that a pair of substantially U-shaped shield members made of metal plates are overlapped on four or three surfaces of the exterior of a substantially box-shaped insulative connector housing.
FIGS. 15 and 16 of this application show such a conventional shielded connector. FIG. 15 illustrates a receptacle style connector R, while FIG. 16 illustrates a plug style connector P. The receptacle connector R is typically smaller in size than the plug connector P, so it should be understood that the drawings are not to scale and that the representative size of the receptacle connector R has been enlarged for clarity.
As for the receptacle connector R of FIG. 15, the shield of the connector is composed of a metal shell 320 that is disposed on the outer surface of the connector housing. It is shaped in a substantially U-shape as viewed from the top and the connector shield also includes a metal shield plate 330 that is U-shaped in cross-section that is disposed between the metal shell 320 and the connector insulative housing. The metal shell 320 is formed so as to cover three surfaces, i.e., the front surface and both side surfaces of the insulative housing, while the shield metal plate 330 is disposed to cover three surfaces, i.e., the top surface and both side surfaces of the insulating housing. Thus four surfaces of the connector housing are actually covered with the shield, i.e., the front surface, the top surface and both side surfaces. An engagement piece 303 is provided on the metal shield plate 320 that is engaged with an engagement recess portion 311 of a terminal portion 310 that serves as a metal shield for opposing the plug connector P.
The metal shell 320 has a front surface shield portion 323 and side surface shield portions 324 on both sides of the connector. An engagement sleeve portion 307 has an opening 321 into which the terminal portion 310 of the plug connector P is inserted, and is provided in the front surface 323 of the shield portion. As illustrated, the engagement sleeve portion 307 is formed substantially into a rectangular sleeve shape so that it projects outwardly on the front surface of the connector. This metal shell 320 is typically formed by drawing that specific portion of the engagement sleeve portion 307, after the entire metal shield plate has been stamped out from a blank. A convex portion 308 may be formed as a polarizing portion that is engaged with a recess 312. Conductive terminals 313, having contact portions are arranged within the plug connector P.
Connectors such as those shown in FIGS. 15 & 16 tend to be small in size, as well as the circuit boards upon which they are mounted. However, it is desirable to reduce the manufacturing cost of such connectors without losing the dimensional stability of the connector. Thus, it is a goal of this invention to keep the connector small in size while maintaining the dimensional stability of the shield and retaining its electrical properties.
However, in the prior art connectors described above and shown in FIGS. 15 & 16, there is a problem. The manufacturing cost of these connectors is high because the engagement sleeve portion 307 is formed by drawing. The outer profile of these connectors is also increased because of this drawn structure, resulting in difficulty in achieving the goal of miniaturization. The engagement sleeve portion 307 is formed by drawing so that there is a problem that the sleeve portion 307 does not have satisfactory dimensional stability. Furthermore, a large force, such as a twisting force, may be applied to the engagement sleeve portion 307 when engaged with the plug connector P. The forces generated by repeated removal and insertion may weaken the drawn portions of the connector.
Also, in these type of connectors, it has been found that there is room for improvement by reducing the connector size and the overall weight of the connector, while still maintaining the electrical performance of the shield. The conventional connector housing used with such connectors is formed substantially into a box-like shape with six surfaces. In view of the inherent function of the insulative housing, it is sufficient to have the housing to support the shield member in its extent around the housing and its internal contacts, as well as supporting the contacts. In the aforementioned conventional connectors, although the housing has structure supports the metal shield and has a desired mechanical strength, it has an unnecessarily large thickness for its structural stability. This creates a problem that inhibits the goal of attaining further miniaturization and weight reduction.
Additionally, in this type of connector where repeated removal and insertion of the plug connector P to the receptacle connector R occurs, frictional wear or deformation can occur with the drawn engagement portions, so that there is a fear that the contact stability between the shield members of the plug and receptacle connectors is gradually reduced over time, and frictional wear may result in a displacement between in the two respectively engaged shields, reducing the mechanical stability of the two connectors. For this reason, depending on the frequency and condition of the insertion/removal of the two connectors, there is another fear that either the grounding stability of the overall connector system will be degraded (i.e., the ability of electrical noise to be led by the shields to a ground on the circuit board) as well as the stability of the engagement between the two connectors.
In particular, with respect to the grounding stability problem, due to the displacement between the two shields, there is a fear that the electrical connection between the plug connector and the receptacle connector is unstable and it will be difficult to lead the electrically transmitted noise components to the ground on the circuit board.
It is also possible to form the shields of the connectors by way of die-casting, instead of the drawn members shown. However, the ductility of such die-cast parts is poor as compared to sheet metal and in these size and style connectors, a high precision for engagement desired. In the reduced size, excessive stresses may develop during insertion and removal of the connectors, so that a fear of deforming the drawn or die-cast shield engagement members is real.
The present invention is directed to an improved connector that overcomes the aforementioned disadvantages.